Semiconductor chip package having an adhesive tape attached on bonding wires

ABSTRACT

The invention provides a semiconductor chip package, and a means of forming such a semiconductor chip package, in which one or more semiconductor chips are electrically connected to a mounting substrate by wire bonding in which an adhesive tape is provided on the active surface of the semiconductor chips for encapsulating at least an upper portion of the bonding wires adjacent the active surfaces to improve the stability of the bonding wires during subsequent processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This nonprovisional U.S. patent application is a divisional applicationof and claims priority under 35 U.S.C. § 120 to application Ser. No.11/324,293, filed on Jan. 4, 2006, now U.S. Pat. No. 7,227,086 which isa divisional application of and claims priority under 35 U.S.C. § 120 toapplication Ser. No. 10/458,281 filed on Jun. 11, 2003, now U.S. Pat.No. 7,005,577 which claims priority under 35 U.S.C. § 119 to KoreanPatent Application 2002-55690 filed on Sep. 13, 2002. The entirecontents of all of the above are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device and, moreparticularly, to a semiconductor chip package in which a semiconductorchip is electrically connected to a substrate by wire bonding.Generally, in forming such a package, a semiconductor chip is attachedto a mounting means such as a substrate or lead frame using a liquidadhesive.

FIG. 1 is a cross-sectional view showing an example of a conventionalsemiconductor chip package assembled with a liquid adhesive. FIG. 2 is across-sectional view showing another example of a conventionalsemiconductor chip package assembled with a liquid adhesive.

As illustrated in FIG. 1, a semiconductor chip package 310 includes asingle semiconductor chip 311. The semiconductor chip 311 is attached toa printed circuit board 321 by a layer of liquid adhesive 325. Chip pads312 are connected to substrate pads 322 by bonding wires 327.

As illustrated in FIG. 2, a semiconductor chip package 410 includes twosemiconductor chips in a vertical stack. A first semiconductor chip 411is attached to a printed circuit board 421 using a layer of liquidadhesive 425. A second semiconductor chip 413 is then attached to thefirst semiconductor chip 411 by a layer of liquid adhesive 426. Chippads 412 and 414 and the semiconductor chips are electrically connectedto substrate pads 422 by bonding wires 427.

The semiconductor chip packages 310 and 410 are commonly protected fromexternal environments by sealing portions 335 and 435, respectively. Thesealing portions 335 and 435 are typically made of an epoxy moldingcompound (EMC). The sealing portions 335 and 435 seal the semiconductorchips 311, 411 and 413, the bonding wires 327 and 427, and theconnection portions of the semiconductor chips and bonding wires. Solderballs 337 and 437 are attached on the bottom surface of the printedcircuit boards 321 and 421 and function as external connectionterminals.

In the conventional semiconductor chip packages illustrated in FIGS. 1and 2, the semiconductor chips are attached using a liquid adhesive. Theuse of liquid adhesive in assembling chip packages may introduceprocessing complications including the need to maintain a uniformquantity of adhesive to reduce voids under the chip and to reduceadhesive overflows onto the semiconductor chip and substrate. Thepresence of such defects may degrade the reliability of the finalsemiconductor product. Further, when a semiconductor chip package isproduced by vertically stacking a plurality of semiconductor chips, theliquid adhesive may contaminate the semiconductor chip pads and possiblycomplicate or degrade the performance of subsequent processes or thereliability of the resulting semiconductor device.

In an effort to address some of the problems associated with liquidadhesives, film-type non-conductive adhesive tape has been used toreplace liquid adhesive for mounting semiconductor chips. FIG. 3 is across-sectional view of an example of a conventional semiconductor chippackage using an adhesive tape for mounting the semiconductor chip.

As illustrated in FIG. 3, a semiconductor chip package 510 includes twosemiconductor chips 511 and 513 provided in a vertical stack. A firstsemiconductor chip 511 is attached to a printed circuit board 521 by aliquid adhesive layer 525. A second semiconductor chip 513 is attachedto the first semiconductor chip 511 by a non-conductive adhesive tape526. The adhesive tape 526 is sized to be located generally within chippads 512 of the first semiconductor chip 511, and with a thickness thatprovides a space for the wire loop portion of bonding wires 527 bconnecting the chip pads 512 to substrate pads 522.

In attaching a semiconductor chip using an adhesive tape, however,misalignment may result in the adhesive tape covering a portion of thechip pads or extending beyond the chip edge so that the wires may not bebonded normally to the chip pads. Furthermore, the empty space remainingbetween the upper chip and the lower chip at their periphery maycompromise the process of attaching bonding wires to the upper chipresulting in poor bonds and/or damaged chips and may result in voids inthe EMC.

SUMMARY OF THE INVENTION

Exemplary embodiments of the invention provide semiconductor chippackages having an adhesive tape attached to the bonding wires near thechip pads. A semiconductor chip package manufactured according to anexemplary embodiment of the invention may include a semiconductor chiphaving an active surface with chip pads formed near the edges of theactive surface. The semiconductor chip is typically mounted on amounting means in such a manner that the active surface of thesemiconductor chip faces upwardly with a plurality of bonding wireselectrically connecting the semiconductor chip to the mounting means. Anon-conductive adhesive tape is attached to the active surface of thesemiconductor chip and onto at least a portion of the bonding wireslocated near the upper portion of the semiconductor chip. A package bodymay then be used to seal the semiconductor chip, the mounting means, thebonding wires, and the non-conductive adhesive tape.

In another exemplary embodiment, the semiconductor chip packagecomprises a plurality of semiconductor chips, each of which has anactive surface with chip pads formed on the active surface. A firstsemiconductor chip is mounted on a mounting means, with bonding wireselectrically connecting the first semiconductor chip to the mountingmeans. The first semiconductor chip may be attached to the mountingmeans by a layer of liquid adhesive. A second semiconductor chip is thenattached to the first semiconductor chip using a non-conductive adhesivetape. A second non-conductive adhesive tape is then applied to theactive surface of the second semiconductor chip. The resulting chipstack structure has adhesive tape attached to the active surface of eachof the semiconductor chips and to an upper portion of the bonding wireslocated near the active surface of each semiconductor chip.

Preferably, the adhesive tape is larger than the active surface of thesemiconductor chip and has a thickness of 5 μm to 200 μm. It is alsopreferable that the adhesive tape comprises a synthetic resin comprisingat least one resin selected from polyimide, epoxy, and acryl resins. Inaddition, the adhesive tape is preferably attached to the entire activesurface in a manner that encloses at least the portion of the bondingwires extending over the upper portion of the semiconductor chip.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will become readilyapparent by the following detailed description, with reference to theaccompanying drawings, in which identified reference numerals designatesimilar or identical structural elements, and, in where:

FIG. 1 is a cross-sectional view showing one example of a conventionalsemiconductor chip package using a liquid adhesive;

FIG. 2 is a cross-sectional view showing another example of aconventional semiconductor chip package using a liquid adhesive;

FIG. 3 is a cross-sectional view showing an example of a conventionalsemiconductor chip package using an adhesive tape;

FIG. 4 is a cross-sectional view of a semiconductor chip package inaccordance with a first exemplary embodiment of the invention;

FIG. 5 is a plane view of a semiconductor chip package in accordancewith a first exemplary embodiment of the invention;

FIGS. 6 and 7 are cross-sectional views along line I′-I″ of FIG. 4illustrating alternative attachments of an adhesive tape to asemiconductor chip package according to the embodiment illustrated inFIG. 4;

FIG. 8 is a cross-sectional view of a semiconductor chip package inaccordance with a second exemplary embodiment of the invention;

FIG. 9 is a cross-sectional view of a semiconductor chip package inaccordance with a third exemplary embodiment of the invention; and

FIGS. 10 and 11 illustrate adhesive tapes according to an exemplaryembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described more fully with reference toexemplary embodiments and the accompanying drawings. This invention may,however, be embodied in many different forms and should not be construedas limited to the exemplary embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art.

FIRST EXEMPLARY EMBODIMENT

FIG. 4 is a cross-sectional view of a semiconductor chip package inaccordance with a first exemplary embodiment of the present invention.FIG. 5 is a plane view of a semiconductor chip package in accordancewith a first exemplary embodiment of the present invention and FIGS. 6and 7 are cross-sectional views illustrating the attachment of anadhesive tape to the semiconductor chip package of FIG. 4.

Referring to FIGS. 4 and 5, a semiconductor chip package 10 includes asemiconductor chip 11 mounted on a printed circuit board 21 using alayer of liquid adhesive 25. Chip pads 12 and substrate pads 22 areelectrically connected by bonding wires 27. An adhesive tape 31comprising a non-conductive synthetic resin is attached to the activesurface of the semiconductor chip 11. The semiconductor chip 11, bondingwires 27 and their connection portions are then further protected fromthe external environment by a sealing portion 35 typically formed froman EMC. Solder balls 37 are provided on the bottom surface of theprinted circuit board 21 as external connection terminals.

The non-conductive adhesive tape 31 is preferably sized larger than theactive surface of semiconductor chip 11 so as to cover both the upperportion of bonding wires 27 extending over the upper surface of the chipand a predetermined length of bonding wires 27 extending outwardly fromthe sides of the chip. The adhesive tape 31 preferably has a thicknessof about 5 μm to 200 μm. If the thickness of the adhesive tape 31 isless than about 5 μm, handling difficulties may increase whilethicknesses in excess of 200 μm can render the thickness of the wholepackage excessive.

In this exemplary embodiment, predetermined portions of the bondingwires 27 are generally fixed in place by the adhesive tape 31 and will,therefore, tend to maintain the spacing and orientation relative toadjacent bonding wires 27. Thus, the bonding wires 27 are less likely toexperience sagging or sweeping during processing subsequent to the tapebonding process.

The adhesive tape 31 is preferably formed of a material sufficientlysoft and thick as to have no damaging effect as it is applied to thebonding wires 27. As shown in FIGS. 6 and 7, the adhesive tape 31 a, 31b may initially be attached to the active surface of the semiconductorchip 11 and extend along the upper surfaces of the bonding wires 27.However, depending on the particular adhesive tape composition, tapethickness, the temperature(s) and the heating cycle utilized, theadhesive tape can remain generally attached on the upper surfaces of thebonding wires 27, as illustrated by adhesive tape 31 a in FIG. 6, or mayexhibit sufficient flow that the adhesive tape can surround the bondingwires 27, as illustrated by adhesive tape 31 b in FIG. 7.

The adhesive tape, in the form of sheet, is preferably made of athermosetting or thermoplastic synthetic resin such as a polyimide,epoxy or acryl resin, or a composite material, for example, as shown inFIGS. 10 and 11, having at least one synthetic resin as a primarycomponent, which has adhesive properties when heated but which willremain solid at the operating temperatures anticipated for the resultingsemiconductor device. As shown in FIGS. 10 and 11 the composite materialmay include polymide resin 132 a and epoxy resin 132 b as shown in FIG.10 or a polymide resin 131 a and a thremoplastic resin as shown in FIG.11. Such materials may allow the adhesive tape to be easily attachedwhen heated using one or more convective, conductive or radiatingheating means. Adhesive tapes such as Model 1595 from 3M and Polyimideseries tapes from Hitachi Chemical Co., Ltd. may be used for thispurpose. In general, adhesive tapes that may be utilized in theinvention will begin to flow at temperatures between about 100° C. andabout 300° C. depending on the particular composition and structureselected. The heating may also be achieved with a thermal-compressingdevice used for applying the adhesive tape or a heater block in which,or adjacent to which, a tape-attaching apparatus is arranged. Duringthermal-compressing processes, care should be taken to avoid pressingthe adhesive tape too strongly against the inner portion of chip pads orabove the bonding wires to reduce the risk of damage to the bondingwires.

The wire bonding may be preferably preformed using stitch bonding of thewire to the chip pads and ball bonding of the wire to the substratepads. Wire bonding may, however, also utilize ball bonding on the chippads and stitch bonding on the substrate pads. Although the adhesivetape is preferably larger than the semiconductor chip, the adhesive tapemay be almost identical to the size of the semiconductor chip. When theadhesive tape is sized to match the semiconductor chip, the adhesivetape will typically extend over only those portions of the bonding wiresthat extend over the active surface.

SECOND EXEMPLARY EMBODIMENT

FIG. 8 is a cross-sectional view of a semiconductor chip package inaccordance with a second exemplary embodiment of the invention. Asillustrated in FIG. 8, a semiconductor chip package 110 includes twosemiconductor chips 111 and 113 of substantially the same size. Thesemiconductor chips 111 and 113 form a vertical stack on printed circuitboard 121 with each of the semiconductor chips 111 and 113 beingelectrically connected to the printed circuit board 121 by bonding wires127 b or 127 a bonded between chip pads 112 and 114 and substrate pads122. Solder balls 137 are attached to a surface of the printed circuitboard 121 opposite the semiconductor chips and are used as externalconnection terminals.

A first semiconductor chip 111 is attached to the printed circuit board121 using a layer of liquid adhesive 125. A second semiconductor chip113, however, is attached to the first semiconductor chip 111 using anadhesive tape 131. Another adhesive tape 132 is then attached to theactive surface of the second semiconductor chip 113. Each of theadhesive tapes 131 and 132 preferably has a thickness of about 5 μm to200 μm and is formed of a non-conductive synthetic resin material. Bothof the adhesive tapes 131 and 132 are preferably larger than therespective surfaces of semiconductor chips 111 and 113 to which they areapplied. The adhesive tapes 131 and 132 also preferably cover theportion of bonding wires 127 b and 127 a extending above the activesurface and a predetermined length of the bonding wires extendingoutwardly from the sides of the semiconductor chips 111 and 113.

The two adhesive tapes 131 and 132 may have substantially differentcompositions or different structures that cause the two adhesive tapesto have different thermal characteristics. For example, using twodifferent adhesive tapes that begin to flow at different temperaturesmay allow an increased degree of control in the chip mounting process.If the first adhesive tape 131 has a flow temperature that is higherthan the flow temperature of the second adhesive tape 132, theattachment to or encapsulation of the lower bonding wires 127 b by thefirst adhesive tape can be completed before attaching the secondadhesive tape. The second adhesive tape 132 can then be applied to theupper surface of the second semiconductor chip 113 and heated to atemperature sufficient to cause the second adhesive tape to attach to orencapsulate the upper bonding wires 127 a without causing additionalflow within the first adhesive tape 131. Conversely, the two adhesivetapes may be selected to have substantially identical thermal behaviorso that a single thermal treatment performed after both the firstadhesive tape 131 and the second adhesive tape 132 are in place willcause the adhesive tapes to attach to or encompass the respectivebonding wires 127 b, 127 a substantially simultaneously.

In this exemplary embodiment, no significant empty space or voids arepresent between the upper semiconductor chip 113 and the lowersemiconductor chip 111. The adhesive tapes can support and resist theforces generated by a bonding tool during a wire-bonding process afterattaching the upper semiconductor chip. Thus, the connection state ofthe bonding wires is generally more consistent and the likelihood ofbonding failures can be reduced. Moreover, by using an adhesive tape onthe upper semiconductor chip, even though the length of bonding wires isincreased due to the stacking of chips, the tendency of the bondingwires to sag or sweep can be reduced. In addition, by using an adhesivetape that is larger than the active surface of the lower semiconductorchip, interference between bonding wires coupled to the upper chip andthe lower chip, respectively, can be reduced.

THIRD EXEMPLARY EMBODIMENT

FIG. 9 is a cross-sectional view of a semiconductor chip package inaccordance with a third exemplary embodiment of the invention. Asillustrated in FIG. 9, a semiconductor chip package 210 includes twosemiconductor chips 211 and 213 of different size. The semiconductorchips 211 and 213 form a vertical stack on printed circuit board 221,with the first semiconductor chip 211 being attached to the printedcircuit board 221 with a layer of liquid adhesive 225. A smaller secondsemiconductor chip 213 is then attached to the first semiconductor chip211 using an adhesive tape 231. The semiconductor chips 211 and 213 areelectrically connected to the printed circuit board contacts 222 bybonding wires 227 b and 227 a and solder balls 137 are provided on asurface of the printed circuit board 221 opposite the semiconductorchips for use as external connection terminals.

According to the exemplary embodiments of the invention, a semiconductorchip package may be formed using stacked semiconductor chips of the samesize or semiconductor chips having different sizes. When the stackedsemiconductor chip package includes chips of different sizes, it ispreferred that the upper semiconductor chip is smaller than the lowersemiconductor chip.

Although the exemplary embodiments show a printed circuit board used asthe mounting means, a film type tape circuit board or conventional leadframes may also be used as mounting means. Also, although the adhesivetape is preferably larger than the active surface of the semiconductorchip to which it is attached, the adhesive tape may be substantially thesame size or slightly smaller than the active area of the semiconductorchip to which it is attached. Further, although in the describedexemplary embodiments the initial attachment of the first or solesemiconductor chip to the substrate used a liquid adhesive, an adhesivetape could be used to provide the initial attachment. Although exemplaryembodiments have been illustrated with semiconductor chip packageshaving two semiconductor chips, the invention is equally applicable tosemiconductor chip packages including stacks of more than twosemiconductor chips.

It should be understood that this invention is not to be limited to theexemplary embodiments and examples described above, and that numerousmodifications and variations can be made by those skilled in the artwithout departing from the spirit and scope of this invention.

1. A method of assembling a semiconductor chip package comprising:attaching a first semiconductor chip having a first surface and anactive surface opposite the first surface on a mounting means; attachinga first plurality of bonding wires between chip pads arrayed within aperimeter of the active surface of the first semiconductor chip andmount pads arrayed on the mounting means, the first plurality of bondingwires establishing electrical connections between the firstsemiconductor chip and the mounting means; attaching a first adhesivetape to the active surface of the first semiconductor chip and to upperportions of the first plurality of bonding wires; and heating the firstadhesive tape to a temperature sufficient to cause portions of the firstadhesive tape to encapsulate the upper portions of the bonding wireswithin the first adhesive tape.
 2. A method of assembling asemiconductor chip package according to claim 1, wherein heating thefirst adhesive tape is accomplished using at least one heating techniqueselected from thermo-compression, radiation, conduction and convection.3. A method of assembling a semiconductor chip package according toclaim 1, further comprising: encapsulating the first semiconductor chip,the first plurality of bonding wires and the first adhesive tape in apolymeric composition; and curing the polymeric composition.
 4. A methodof assembling a semiconductor chip package according to claim 1, furthercomprising: attaching a second semiconductor chip having a first surfaceand an active surface opposite the first surface to the firstsemiconductor chip, the attachment being substantially maintained by thefirst adhesive tape; attaching a second plurality of bonding wiresbetween chip pads arrayed within a perimeter of the active surface ofthe second semiconductor chip and mount pads arrayed on the mountingmeans, the second plurality of bonding wires establishing electricalconnections between the second semiconductor chip and the mountingmeans; attaching a second adhesive tape to the active surface of thesecond semiconductor chip and to upper portions of the second pluralityof bonding wires; and heating the second adhesive tape to a temperaturesufficient to encapsulate the upper portions of the second plurality ofbonding wires within the second adhesive tape.
 5. A method of assemblinga semiconductor chip package according to claim 4, wherein: heating thefirst adhesive tape to encapsulate the first plurality of bonding wiresand heating the second adhesive tape to encapsulate the second pluralityof bonding wires are performed substantially simultaneously.
 6. A methodof assembling a semiconductor chip package according to claim 4, whereinheating the first adhesive tape is conducted at a first temperature andheating the second adhesive tape is conducted at a second temperature;wherein the second temperature is insufficient to cause the firstadhesive tape to encapsulate the first plurality of bonding wires.
 7. Amethod of assembling a semiconductor chip package according to claim 4producing a semiconductor chip package further comprising, heating thesecond adhesive tape to a temperature sufficient to encapsulate theupper portions of the second plurality of bonding wires within thesecond adhesive tape.
 8. A method of assembling a semiconductor chippackage according to claim 1 producing a semiconductor chip packagecomprising: a first semiconductor chip having a first surface and anactive surface opposite the first surface; chip pads arrayed within aperimeter of the active surface; a mounting means having a mountingregion to which the first surface of the semiconductor chip is affixedand a plurality of mount pads arrayed on the mounting means; firstplurality of bonding wires providing electrical connection between chippads and mount pads, upper portions of the first plurality of bondingwires extending from the chip pads and above and across a peripheralregion of the active surface; and a first adhesive tape attached to theactive surface of the first semiconductor chip and substantiallyencapsulating the upper portions of the first plurality of bondingwires.
 9. A method of assembling a semiconductor chip package accordingto claim 1 producing a semiconductor chip package further comprising,heating the first adhesive tape to a temperature sufficient to causeportions of the first adhesive tape to encapsulate the upper portions ofthe bonding wires within the first adhesive tape.